Method of making abrasive articles



Patented Feb. 16 1926.

UNITED STATES PATENT OFFICE.

MINER HARTMANN, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO THE CAR- BOQRUNDUM COMPANY, OF NIAGARA FALLS. NEW YORK, A CORPORATION OF PENNSYLVANIA.

, lJllIIlilTHOD OF MAKING ABRASIVE ARTICLES.

. No Drawing.

To all whom it may concern:

Be it known that I, MINER L. HARTMANN, a citizen of the United States, residing at Niagara Falls, county of Niagara, and State of New York, have invented a new and use ful Improvement in Methods of Maklng 'Abrasive Articles, of which the following is a full, clear, and exact description.

The present invention relates broadly to an improved method for making abrasive implements or articles in'which the abrasive or absorption in porous blocks, and after thorough drying the pieces are cut to desired sizes and burned in ceramic kilns. An open porous structure is thus secured. The process, however, is slow and expensive and requires highly skilled labor.

To overcome some of the inherent di-fficulties of the so-called puddle process, a process of pressing the damp mixture of abrasive grain and bond has been widely used. While this process is rapid, and less expensive than the puddle process, the

art-icles produced, such as grinding wheels,

are too close or dense and the wheels do not cut freely in grinding operations. Such articles are not always satisfactory either as to uniformity or structure.

I have discovered that these inherent objections and faults of the pressed process of making abrasive articles may be overcome by adding to the mixture from which the articles are to. be made, suitable proportions of a material which during the kiln firing of the articles is removed by volatilization and oxidation, leaving suitable voids or pore spaces in the wheelstructure. For this purpose,'the most available and satis- 4 factory material is a comminuted nonmelt ing' organic material such as wood fibre and flour. The degree .of comminution of the wood depends upon the effect desired and Application filed July 13, 1923. Serial No. 651,430.

An additional advantage arises from the marked effect upon the structure of the bond ing material itself, apparently due to the prevention or coalescing of the separate bond particles during the firing, and a consequent maintenance of a somewhat porous network in the bond itself.

lVood flour made from hardwood, and more particularly oak, is preferred, since during heating it does not swell nor give off excessive amounts of liquid or volatile materials, but on the other hand is quietly charred and subsequently removed by oxidation.

As an illustration of In process, I may take 80 parts by weight 0 an abrasive material, such as fused aluminous abrasive grains of a size corresponding to a 20 mesh screen. With this I may mm 20 parts by weight of finely divided bond consisting of 35 per cent Albany clay and per cent plastic ball clay, and 2 parts of oak wood flour, all of which is 60 mesh and finer. After thorough dry mixing, this may be moistened with sufiicient water to make it workable, about 4 per cent, after which it is put into suitable molds and pressed in a hy raulic press to about 1000 pounds per square inch. After removal from the mold produces an article having much better cutting ualities. Mixtures containing the wood our are also more easily pressed to a uniform structure than withoutithe wood flour, thereb making possible an improvement in uni ormity of finished roduct.

While I have described the a ove particular illustration of my invention, it is not grains are held by a vitrified ceramic bonding agent.

- Gertainadvantages of thepresent invention arise from the provision of a mixture more easily shaped and insuring gr'eater unia formity of product.

Further advantages arise from the provision of an abrasive article or implement having improved abrasive qualities.

I claim:

1'. In the process of making bonded abrasive articles, the steps consisting in addin to a raw mixture of abrasive grains and bond, comminuted non-volatile organic par ticles which do not have a tendency to swell up during burning, pressing the mixture to the desired shape, and subsequently efi'ect-' ing removal of the organic particles {by burning the shaped article.

2. In the process of making bonded abrasive articles, the steps consisting in adding to a raw mixture of abrasive grains and bond, comminuated hard wood particles,

pressing the mixture to the desired shape, and subsequently effecting removal of the hard Wood particles.

3. In the process of making ceramically bonded abrasive articles, the steps consisting in adding to a raw mixture of fused aluminous abrasive grains and a clay bond, comminuated wood particles, pressing the mixture to the desired shape, and subse- (luently effecting removal of the wood particles.

4. In the process of making ceramically bonded abrasive articleslfthe steps consisting in adding to a raw mixture of fused aluminous abrasive grains and bond, comminuated hard wood particles, pressing the mixture to the desired shape, and subsequently efli'ecting removal of the hard Wood particles.

5. In the process of making ceramic-ally bonded abrasive articles, the steps consisting-in forming a raw mixture of abrasive grains and clay bonding material, adding thereto non-volatile Iorganic particles, shap- I ing the mixture, and then firing the shaped mixture to vitrify the bond and efiect re-- moval of the organic particles by volatilization and oxidation. V In testimony whereof I have hereunto se my hand.

MINER HARTMANN. 

